This application aims to acquire evidence on the role of word knowledge in comprehension skill. Its research aims to identify two components of the word knowledge -comprehension link: (1) the consequences of word knowledge for children's and adults' comprehension processes and, more specifically, the ability to integrate word meanings in text comprehension. (2) How children and adults learn the meanings of new words during reading and how this learning is affected by their comprehension skill. In pursuing these two aims, the project addresses how the relationship between word knowledge (and word learning) and comprehension change across schooling. Its hypothesis is that, despite the skill development that occurs across ages, the general relationship among word knowledge, new word learning, and comprehension is unchanging from middle school to young adulthood. The research methods for these aims require fine-grain measures taken during word-by-word reading and word learning. For this purpose, much of the research used event related potentials (ERPs) measures, which are voltage shifts measure on the scalp surface in response to specific experimental events. For example, ERPs taken during text reading reveal voltage shifts that indicate how readily the reader is able to integrate the meaning of the word with the prior text. This indicator, furthermore, appears more robustly for readers of high comprehension skill than for readers of low comprehension skill. As a second example, ERP measures can produce indicators of new word learning. After learning the meaning of a new word, ERPs recorded when the new word is viewed show specific markers of the learning experience and of the use of the newly learned meaning in a meaning judgment task. Further, the robustness of the learning signal produced by the new word is related to the comprehension skill of the reader. The research takes advantage of these observations in a series of studies with both children and adults, whose word knowledge and comprehension skill are assessed and related to outcomes of the experiments. The studies are designed to gain important results that will increase understanding of how individual skill is related to processes of word-by-word comprehension and the ability to learn the meanings of new words through reading. The work of the project has implications for the broad health-related goals of NIH, especially in contributing to research on the psychological, language and educational development of children. PUBLIC HEALTH RELEVANCE This project will obtain important scientific information on children's and adults' reading comprehension, especially the importance of word knowledge and learning new words as components of reading skill. The work of the project has implications for the broad health-related goals of NIH, especially in contributing to research on the psychological, language and educational development of children.